Emission concerns associated with the operation of internal combustion engines, generally, but not always, diesel engines, have resulted in an increased emphasis on the use of exhaust gas heat exchange systems with such engines, particularly, but not always, in vehicular applications. These systems are employed as part of an exhaust gas recirculation (EGR) system by which a portion of an engine's exhaust is returned to its combustion chambers via its intake system. The result is that some of the oxygen that would ordinarily be inducted into the engine as part of its fresh combustion air charge is displaced with inert gases thus reducing the rate of NOx formation. EGR systems are frequently designed to absorb heat from the combustion process, thus lowering its temperature and providing a further reduction in NOx.
In many applications employing EGR systems, exhaust gas recirculation coolers are employed. In the usual case, engine coolant is brought into heat exchange relation with the exhaust gas prior to its recirculation so as to lower its temperature. While many of the known coolers may work well for their intended purpose, there is always room for improvement.